Biocompatible controlled release coatings for medical devices and related methods

a controlled release and medical device technology, applied in medical science, medical preparations, surgery, etc., can solve the problems of few potential polymer compositions possessing all the desired properties, and the design of biocompatible polymer coatings has been largely a process of trial and error, and achieves high elasticity/ductility.

Active Publication Date: 2005-04-21
MEDTRONIC VASCULAR INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0029] The compatible polymeric controlled release coatings made in accordance with the teachings of the present invention can be made form any combination of polymers that combine to form novel polymer compositions that exhibit the combined properties of biocompatibility, high elasticity / ductility, resistance to erosion, elasticity, and controlled drug release. Suitable non-limiting exemplary monomers include hydroxy alkyl methacrylate, N-vinyl pyrrolidinone, alkyl methacrylate, vinyl alcohols, acrylic acids, acrylamides, ethylene, vinyl acetate, ethylene glycol di(meth)acrylate, methacrylic acid and terpolymers, co-polymers and homopolymers thereof.

Problems solved by technology

However, designing polymer coatings for medical devices have proven problematic.
Additionally, when the medical device comes into intimate contact with unprotected tissues such as blood and internal organs it must also be biocompatible.
Presently, designing a biocompatible polymer coating having the desired physical and chemical properties has been largely a process of trial and error.
However, very few potential polymer compositions will possess all of the desired properties required for a medical device controlled release coating.
Consequently, present controlled release coating development processes are tedious, time consuming and seldom result in an optimized medical device coating having the combination of biocompatibility, ductility, surface adhesiveness and drug-polymer solubility.

Method used

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  • Biocompatible controlled release coatings for medical devices and related methods
  • Biocompatible controlled release coatings for medical devices and related methods
  • Biocompatible controlled release coatings for medical devices and related methods

Examples

Experimental program
Comparison scheme
Effect test

example 1a

General Method of the Two-Step Synthesis of Segmented n-Butyl Methacrylate and Vinyl Acetate Copolymers

[0105] One embodiment of the present invention is exhibited by a two-step synthesis of a copolymer with n-butyl methacrylate and vinyl acetate segments. In the first step of the synthesis, predetermined amounts of n-butyl methacrylate (BMA) and vinyl acetate (VAc) were mixed in a pre-dried glass reactor equipped for mechanical stirring while providing a nitrogen environment on the reactants. The mixture was then sparged with nitrogen for about five minutes. A requisite amount of azo-bis-butyronitrile (Azo) was added to the mixture. In most cases, isopropyl alcohol (IPA) sparged with nitrogen was also added to the mixture. The mixture was heated to the desired temperature under nitrogen and stirred for a certain period of time until the commencement of the second step.

[0106] In the second step of the synthesis, a second aliquot of the Azo free radical initiator and IPA were added ...

example 1b

General Methods of Analysis

[0108] A set of general analysis methods was used to monitor and characterize the polymerization reactions. In-process monitoring of the polymerization reaction was achieved by the analysis of residual monomers and molecular weight build-up using gel permeation chromatography (GPC) with dichloromethane as a solvent.

[0109] The purified copolymer was characterized with infrared analysis using a film prepared from a chloroform solution. The composition of the purified copolymer was determined with nuclear magnetic resonance (NMR), using CDCL3 as a solvent. Number average (Mn) and weight average (MW) molecular weights were measured using GPC with dichloromethane (DCM) or tetrahydrofuran (THF) as a solvent, and the inherent viscosity (I.V.) with chloroform.

example 1c

General Method of Film Formation and Determination of Percent Elongation

[0110] Fracture strain characteristics of the polymeric material may be measured by forming the polymer into a sheet, and applying strain to a sample of the material, and determining when the sample breaks, thereby determining the fracture strain.

[0111] The dried polymer was compression-molded into a film about 0.1 mm thick using a heated laboratory Carver press. The temperature, pressure, and time used varied with the copolymer composition—typically above 50° C., 3,000 lbs, and 2 minutes, respectively. The pressed polymer was then quick-quenched to about 25° C. and removed. The molded film was cut into 13×40 mm pieces. The percent elongation was determined on a Mini-Bionix Universal Tester using a gauge length of 19 mm and strain rate of 0.5 mm / s.

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Abstract

Biocompatible coatings for medical devices are disclosed. Specifically, polymer coatings designed to control the release of bioactive agents from medical devices in vivo are disclosed wherein the solubility parameters of polymers and drugs are closely matched to control elute rate profiles. The present application also discloses providing vascular stents with controlled release coatings and related methods for making these coatings.

Description

RELATED APPLICATION [0001] This application is a continuation-in-part of Patent Cooperation Treaty patent application number PCT / US04 / 26516 filed Aug. 12, 2004 which claims priority to U.S. Provisional Patent Application Ser. No. 60 / 495,143 filed Aug. 13, 2003, now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 10 / 393,880 filed Mar. 20, 2003.FIELD OF THE INVENTION [0002] This invention relates generally to biocompatible coatings for medical devices. More specifically, the present invention relates to polymer coatings designed to control the release of bioactive agents from a medical device. Even more specifically the present invention relates to providing vascular stents with controlled release coatings and related methods for making these coatings. BACKGROUND OF THE INVENTION [0003] Medical devices are used for myriad purposes on and throughout an animal's body. They can be simple ex vivo devices such as adhesive bandages, canes, walkers and contact ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61F2/00
CPCA61L31/10A61L31/16A61L2300/602A61L2300/416A61L2300/406
Inventor UDIPI, KISHORECHENG, PEIWENCHEN, MINGFEILYU, SU-PING
Owner MEDTRONIC VASCULAR INC
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